Fuel pump not working when safety switch connected

Curious. I’m a very new owner of a 85 QV (UK spec) -where is this safety switch?

 

Can also be caused by a bad relay. There are two relays associated with the fuel pump operation: the ...113 fuel pump relay (which is OK since you report things work with the safety switch unplugged) and a ...101 relay (Relay F - called the "start electro-valve control relay" in the euro QV OM) that controls the fuel pump relay depending on the state of the safety switch and if the starter motor is cranking. Just "borrow" another ...101 relay for a test (say, from a headlight function), and see if putting another/different ...101 relay in the Relay F position helps, or not.

 

You can check the unplugged safety switch resistance:
When engine not running (airflow plate not deflected) = should be 0 Ohms (or just a few Ohms) between the two terminals.
When the engine is running (airflow plate deflected) = should be infinite Ohms between the two terminals.
But the more typical failure is getting infinite Ohms (like an unplugged safety switch) so the engine should always start and run in that case.

When you try starting (with the safety switch plugged in), does it:

1. just crank and never fire at all,
or
2. does it fire up, but die when you release the key to run?

 

Thanks I've found it. No mention of it in either my handbook or my QV workshop manual (which shows nothing abut the fuel system). I did find it in the Mondial WSM you kindly linked to.- Buried in a test procedure for checking the fuel pump works!

 

You can also test with air cleaner off, safety switch connected, ignition switch on then press down on the air pate and fuel pump should run.

 

he said another pic of the safety switch like Stephan,s pic.

Image Unavailable, Please Login

 

Thanks for posting that pic. I like it also showing the "rubber plug with a wire handle" for blocking the idle mixture screw access hole. Much better than the stock plastic anti-tamper cap (which is often lost/missing). Where did you source it? RockAuto, Volvo, somewhere else?

 

You’re welcome Steve, this is where I got them from: https://store.delorean.com/catalogsearch/result/?q=102392a
I remember my old VW Golf had one I just don’t know the P/N for VW.

 

Thanks as it also shows the idle mixture screw location. (Thread Emissions Test results)

 

Hello,

I am having the same issue with my 1986 328 GTS and I would
Ike to replace the blue AFM switch. I searched the Ricambi America parts diagram and cannot find it ( and the part number for the blue switch). Would anybody have the part number for this switch.

This would greatly be appreciated.

Thank you,
Angel

 

The blue AFM switch is considered part of the AFM unit, and doesn't have its own part number (and it's really a bunch of different parts working together rather than a self-contained switch assembly -- see the Mondial8/QV WSM for a drawing of how it works). Maybe if a F parts dismantler (or another marque dismantler that also uses Bosch CIS) has an AFM unit with some other problem (like a broken airflow flap pivot mechanism), you could get the various parts that you might need -- just a thought...

 

Good evening Steve,

Thank you for the explanation and guidance.

Best regards,
Angel